Thursday, August 16, 2012

Laser diode controller for a CNC mill

Laser diode controller for a CNC mill:
[Smells of Bikes] wanted to add laser etching to the list of tricks his home CNC setup is capable of. He has a diode which will work for the task, but he needed a driver that could be interfaced with the CNC system. He ended up designing a driver board based around the LM3402 chip.
Now driving one of these laser diodes isn’t all that different from driving a Light Emitting Diode. He chose to use the LM3402 chip because he’s the TI engineer who designed the official evaluation board for the part. It’s meant for high-power LED applications, and the 700 mA he needs for the laser is within spec. Since he’s soldering by hand, and this part has a ground pad on the bottom, he shares his soldering technique in detail. Once the driver board is ready, he uses a ‘sed’ command to replace the g-code Z axis commands with digital on/off commands to switch the diode.
Check out the demo video after the break. He uses a diffuse beam since the cutting beam is bright enough to damage his camera.